Dropping Redo Log Members

hi
in Oracle documentation they said you can't drop a member if it's an active
but i tried it in Oracle's Database 10g and it's dropped successfully
what happend ?
The link is :
http://download.oracle.com/docs/cd/B28359_01/server.111/b28310/onlineredo005.htm
Thanks

>
but i tried it in Oracle's Database 10g and it's dropped successfully >
You would have done alter system switch logfile before dropping the active redo logsfile.
Refer to the link for the status of the redo logs [http://download.oracle.com/docs/cd/B14117_01/server.101/b10755/dynviews_1126.htm#REFRN30127]
23:36:05 venture >select * from v$log;
    GROUP#    THREAD# SEQUENCE#      BYTES    MEMBERS ARC STATUS           FIRST_CHANGE# FIRST_TIM
         1          1         29 104857600          1 NO INACTIVE               7457724 07-DEC-08
         2          1         30 104857600          1 NO INACTIVE               7794484 08-DEC-08
         3          1         33 104857600          1 NO CURRENT                8016830 09-DEC-08
         4          1         31 104857600          1 NO INACTIVE               8016825 09-DEC-08
         5          1         32 104857600          1 NO INACTIVE               8016827 09-DEC-08
23:38:01 venture >create table test as select rownum id,'TEST' name from dual connect by level <= 10000000;
Table created.
Elapsed: 00:00:20.09
23:39:27 venture >select * from v$log;
    GROUP#    THREAD# SEQUENCE#      BYTES    MEMBERS ARC STATUS           FIRST_CHANGE# FIRST_TIM
         1          1         29 104857600          1 NO INACTIVE               7457724 07-DEC-08
         2          1         30 104857600          1 NO INACTIVE               7794484 08-DEC-08
         3          1         33 104857600          1 NO CURRENT                8016830 09-DEC-08
         4          1         31 104857600          1 NO INACTIVE               8016825 09-DEC-08
         5          1         32 104857600          1 NO INACTIVE               8016827 09-DEC-08
Elapsed: 00:00:00.00
23:39:34 venture >alter database drop logfile group 3;
alter database drop logfile group 3
ERROR at line 1:
ORA-01623: log 3 is current log for thread 1 - cannot drop
ORA-00312: online log 3 thread 1: 'D:\ORACLE\ORADATA\VENTURE\REDO03.LOG'
Elapsed: 00:00:00.01
23:39:51 venture >alter system switch logfile;
System altered.
Elapsed: 00:00:00.01
23:40:02 venture >select * from v$log;
    GROUP#    THREAD# SEQUENCE#      BYTES    MEMBERS ARC STATUS           FIRST_CHANGE# FIRST_TIM
         1          1         34 104857600          1 NO CURRENT                8017910 09-DEC-08
         2          1         30 104857600          1 NO INACTIVE               7794484 08-DEC-08
         3          1         33 104857600          1 NO ACTIVE                 8016830 09-DEC-08
         4          1         31 104857600          1 NO INACTIVE               8016825 09-DEC-08
         5          1         32 104857600          1 NO INACTIVE               8016827 09-DEC-08
Elapsed: 00:00:00.00
23:40:03 venture >alter database drop logfile group 3;
alter database drop logfile group 3
ERROR at line 1:
ORA-01624: log 3 needed for crash recovery of thread 1
ORA-00312: online log 3 thread 1: 'D:\ORACLE\ORADATA\VENTURE\REDO03.LOG'
Elapsed: 00:00:00.00
23:40:11 venture >alter system switch logfile;
System altered.
Elapsed: 00:00:00.01
23:40:25 venture >select * from v$log;
    GROUP#    THREAD# SEQUENCE#      BYTES    MEMBERS ARC STATUS           FIRST_CHANGE# FIRST_TIM
         1          1         34 104857600          1 NO INACTIVE               8017910 09-DEC-08
         2          1         35 104857600          1 NO CURRENT                8018022 09-DEC-08
         3          1         33 104857600          1 NO INACTIVE               8016830 09-DEC-08
         4          1         31 104857600          1 NO INACTIVE               8016825 09-DEC-08
         5          1         32 104857600          1 NO INACTIVE               8016827 09-DEC-08
Elapsed: 00:00:00.00
23:40:28 venture >alter database drop logfile group 3;
Database altered.
Elapsed: 00:00:00.00
23:40:42 venture >select * from v$log;
    GROUP#    THREAD# SEQUENCE#      BYTES    MEMBERS ARC STATUS           FIRST_CHANGE# FIRST_TIM
         1          1         34 104857600          1 NO INACTIVE               8017910 09-DEC-08
         2          1         35 104857600          1 NO CURRENT                8018022 09-DEC-08
         4          1         31 104857600          1 NO INACTIVE               8016825 09-DEC-08
         5          1         32 104857600          1 NO INACTIVE               8016827 09-DEC-08
Elapsed: 00:00:00.00
23:40:46 venture >HTH
Anand

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>
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Hi br00klynZ00,
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Maybe teh CURRENT?!
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Oracle 11gR1 RHEL5 64 bit
Hi,
I was wondering what is better from a perfomance tuning perspective. I have log swiches occuring every 2 minutes in our production database. I know definitely that our log file members are too small (100MB). The redo log sizing tool in OEM told me to make it 40G according to the fast_start_mttr_target setting which is set to 600. Now, my question is what is better to do?
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Hi all,
I'm trying to drop standby logfiles on primary database (other database that I'm configuring the DG).
The members of the standby log groups don't exists on file system.
Somebody have deleted these files. Its old configuration where the files were in file system. Now they are in ASM.
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SQL> alter database clear logfile group 7;
alter database clear logfile group 7
ERROR at line 1:
ORA-19528: redo logs being cleared may need access to files
SQL> select * from v$logfile order by 1;
    GROUP# STATUS TYPE    MEMBER                                                                           IS_
         1         ONLINE +REDO1/proj/onlinelog/group_1.256.340558657                                     NO
         1         ONLINE +REDO2/proj/onlinelog/group_1.256.340558659                                     NO
         2         ONLINE +REDO1/proj/onlinelog/group_2.257.340558879                                     NO
         2         ONLINE +REDO2/proj/onlinelog/group_2.259.340558879                                     NO
         3         ONLINE +REDO1/proj/onlinelog/group_3.258.340558707                                     NO
         3         ONLINE +REDO2/proj/onlinelog/group_3.257.340558709                                     NO
         4         ONLINE +REDO2/proj/onlinelog/group_4.258.340558713                                     NO
         4         ONLINE +REDO1/proj/onlinelog/group_4.259.340558711                                     NO
         5         ONLINE +REDO2/proj/onlinelog/group_5.260.340558965                                     NO
         5         ONLINE +REDO1/proj/onlinelog/group_5.260.340558963                                     NO
         6         ONLINE +REDO1/proj/onlinelog/group_6.261.340558967                                     NO
         6         ONLINE +REDO2/proj/onlinelog/group_6.261.340558967                                     NO
         7         STANDBY /oracle/proj/onlinelog2/redo_702.log                                            NO
         7         STANDBY /oracle/proj/onlinelog1/redo_701.log                                            NO
         8         STANDBY /oracle/proj/onlinelog2/redo_802.log                                            NO
         8         STANDBY /oracle/proj/onlinelog1/redo_801.log                                            NO
         9         STANDBY /oracle/proj/onlinelog2/redo_902.log                                            NO
         9         STANDBY /oracle/proj/onlinelog1/redo_901.log                                            NO
        10         STANDBY /oracle/proj/onlinelog1/redo_1001.log                                           NO
        10         STANDBY /oracle/proj/onlinelog2/redo_1002.log                                           NO
20 rows selected.
SQL> select * from v$standby_log order by 1;
    GROUP# DBID            THREAD# SEQUENCE#      BYTES       USED ARC STATUS     FIRST_CHANGE# FIRST_TIM LAST_CHANGE# LAST_TIME
         7 UNASSIGNED            0          0 104854601        512 YES UNASSIGNED             0                      0
         8 UNASSIGNED            0          0 104854601        512 YES UNASSIGNED             0                      0
         9 UNASSIGNED            0          0 104854601        512 YES UNASSIGNED             0                      0
        10 UNASSIGNED            0          0 104854601        512 YES UNASSIGNED             0                      0What can I do to drop these reference?
Any other solution instead of edit the controlfile and stop/start tghe database?
thank you!!!!

Hello;
Well Oracle thinks the files are there, but I remember a bug on metalink where the controlfile still had them, but they were not on the file system. Can you confirm they exist?
Meanwhile I check my notes for the Oracle doc nunber.
Bug 6128242: TRYING TO DROP STANDBY LOG FAILS WITH ORA-19528
So if you are Oracle 10 this might be the issue.
workaround is to re-create the controlfile without the incorrect logfile. ( Yuk!! )
ORA-01156 When Adding Or Dropping Redo Logs [ID 452152.1]
Best Regards
mseberg
Edited by: mseberg on Oct 31, 2011 5:09 PM

Redo logs status - Invalid

I have added new members to my redo log groups. However, when checking the redo log members' status, all the new members have a status of "Invalid" even after restarting the database.
I have checked that the physical files of the new members are created properly in the directory which is owned by the dba account. The rights are all correct.
Now, I am unable to drop these new redo log members and am at a loss of how to change the status to "Stale" or "Inactive".
Please advise.
Thank you.
Regards,
Dara.

Thanks, guys! It works after performing a log switch.
BTW, I have an error which I am not sure if by adding new members work or is the member really corrupted. Please advise.
The error is :
ORA-00313: open failed for members of log group 1 of thread 1
Thank you.
Regards,
Dara.

Default redo log 100mb???????

hi all
my database is runing in archive mode
(database oracle 9i rel 2)
when i issue
SQL> SELECT * FROM V$LOG;
GROUP# THREAD# SEQUENCE# BYTES MEMBERS ARC STATUS FIRST_CHANGE# FIRST_TIM
1 1 59 104857600 1 NO CURRENT 3519698 20-FEB-04
2 1 57 104857600 1 YES INACTIVE 3477638 20-FEB-04
3 1 58 104857600 1 YES INACTIVE 3479786 20-FEB-04
its funny default size of redo log [b]is 100MB
every archive log file is created on my database of size 100mb.
1.whats the reason of deafult size of 100mb
2.its my production database and i want to change its size to 1mb
plz give some suggestion to change it.because my boss don''t want any mistake.
if solution is drop and recreate then it give me trouble all time when i do this. so plz give suggestion for change its size
thanks
kuljeet pal singh

The sizes for the Redo Logs members are determined by several issues:
1.- The switching time that you want.
2.- The switching time is determined according what is the amount of time ( This represent data ) that you are disposed to lose in case of you lose all redo members of one Redo Log group.
3.- The switching time is determined according as well to the sizes for Archive Redo Logs to store and handle them in a confortable way.
4.- In some occasions if you have redo members with low size like 1m , that can affect the performance of your database.
5.- when they are too long the database has to wait while they archives redo logs are generated.
If you want to change the size of redo members you have to create new redo log groups and after go removing the groups that you do not want. When you are doing this you have to have at least 2 Redo Log Groups.
Joel Pérez
http://otn.oracle.com/experts

Increse of redo log size

Hi,
Please help me to increase the redo log size.
As i am in DB - oracle 10G and OS - Suse linux 10SP2
SQL> SELECT * FROM v$log;
    GROUP#    THREAD# SEQUENCE#      BYTES    MEMBERS ARC STATUS
FIRST_CHANGE# FIRST_TIME
         1          1        358 157286400          2 YES INACTIVE
   2972903289 28-NOV-11
         2          1        359 157286400          2 YES INACTIVE
   2972957401 28-NOV-11
         3          1        357 157286400          2 YES INACTIVE
   2972839164 27-NOV-11
    GROUP#    THREAD# SEQUENCE#      BYTES    MEMBERS ARC STATUS
FIRST_CHANGE# FIRST_TIME
         4          1        360 157286400          2 NO CURRENT
   2973005629 29-NOV-11
SQL> SELECT * FROM v$logfile;
    GROUP# STATUS TYPE
MEMBER
IS_
         4         ONLINE
/oracle/JID/origlogB/log_g14m1.dbf
NO
         4         ONLINE
/oracle/JID/mirrlogB/log_g14m2.dbf
NO
    GROUP# STATUS TYPE
MEMBER
IS_
         3         ONLINE
/oracle/JID/origlogA/log_g13m1.dbf
NO
         3         ONLINE
/oracle/JID/mirrlogA/log_g13m2.dbf
    GROUP# STATUS TYPE
MEMBER
IS_
NO
         2         ONLINE
/oracle/JID/origlogB/log_g12m1.dbf
NO
         2         ONLINE
    GROUP# STATUS TYPE
MEMBER
IS_
/oracle/JID/mirrlogB/log_g12m2.dbf
NO
         1         ONLINE
/oracle/JID/origlogA/log_g11m1.dbf
NO
    GROUP# STATUS TYPE
MEMBER
IS_
         1         ONLINE
/oracle/JID/mirrlogA/log_g11m2.dbf
NO
8 rows selected.
Please help me how to execute for the above query.
Thanks,
Hariharan

Hello
Complete step:
Step 1 SQL> select a.group#, a.member, b.bytes/1024/1024 mb from v$logfile a, v$log b where a.group# = b.group#;
This query will show current group with redo log members and their size.
Step 2 Make the last redo log CURRENT one
To find which group is current at this moment use following query
SQL> select group#, status from v$log;
GROUP#         STATUS
1                    CURRENT
2                    INACTIVE
3                    INACTIVE
4                    INACTIVE
Now as you can see that the first group is marked as current but we need to make group 4 as current. So force group 4 to become current one by switching log file. To switch log file use following query.
SQL> alter system switch logfile;
GROUP#         STATUS
1                     INACTIVE
2                    CURRENT
3                    INACTIVE
4                  INACTIVE
SQL> alter system switch logfile;
GROUP#        STATUS
1                     INACTIVE
2                     INACTIVE
3                     INACTIVE
4                    CURRENT
Step 3 Drop the first online redo log
After making the last online redo log file the CURRENT one, drop the first online redo log:
SQL> alter database drop logfile group 1;
Database altered.
Note:
Be aware that if you are going to drop a logfile group, it cannot be the current logfile group. However, where attempting to drop the logfile group resulted in the following error as a result of the logfile group having an active status:
SQL> ALTER DATABASE DROP LOGFILE GROUP 1;
ALTER DATABASE DROP LOGFILE GROUP 1
ERROR at line 1:
ORA-01624: log 1 needed for crash recovery of instance ORA920 (thread 1)
ORA-00312: online log 1 thread 1: ''
Easy problem to resolve. Simply perform a checkpoint on the database:
SQL> ALTER SYSTEM CHECKPOINT GLOBAL;
System altered.
SQL> ALTER DATABASE DROP LOGFILE GROUP 1;
Database altered.
Step 4 You need to re-create dropped online redo log group with different size. Use the following query to achieve this.
SQL> alter database add logfile group 1 ('<path>/origlogA/log_g11m1.dbf','<path>/mirrlogA/log_g11m2.dbf') size 200M reuse;
Database altered.
Step 5 Force another log switch
After re-creating the online redo log group, force a log switch. The online redo log group just created should become the "CURRENT" group:
SQL> select group#, status from v$log;
GROUP#         STATUS
1                     UNUSED
2                     INACTIVE
3                     INACTIVE
4                    CURRENT
SQL> alter system switch logfile;
SQL> select group#, status from v$log;
GROUP#         STATUS
1                      CURRENT
2                      INACTIVE
3                      ACTIVE
Step 6 # Loop back to Step 3 until all logs are rebuilt
After re-creating an online redo log group, continue to re-create (or resize) all online redo log groups until all of them are rebuilt.
Regards,
Rajan

Question about how Oracle manages Redo Log Files

Good morning,
Assuming a configuration that consists of 2 redo log groups (Group A and B), each group consisting of 2 disks (Disks A1 & A2 for Group A and Disks B1 and B2 for group B). Further, let's assume that each redo log file resides by itself in a disk storage device and that the device is dedicated to it. Therefore in the above scenario, there are 4 disks, one for each redo log file and, each disk contains nothing else other than a redo log file. Furthermore, let's assume that the database is in ARCHIVELOG mode and that the archive files are stored on yet another different set of devices.
sort of graphically:
    GROUP A             GROUP B
      A1                  B1
      A2                  B2The question is: When the disks that comprise Group A are filled and Oracle switches to the disks in Group B, can the disks in Group A be taken offline, maybe even physically removed from the system if necessary, without affecting the proper operation of the database ? Can the Archiver process be temporarily delayed until the disks (that were removed) are brought back online or is the DBA forced to wait until the Archiver process has finished creating a copy of the redo log file into the archive ?
Thank you for your help,
John.

Hello,
Dropping Log Groups
To drop an online redo log group, you must have the ALTER DATABASE system privilege. Before dropping an online redo log group, consider the following restrictions and precautions:
* An instance requires at least two groups of online redo log files, regardless of the number of members in the groups. (A group is one or more members.)
* You can drop an online redo log group only if it is inactive. If you need to drop the current group, first force a log switch to occur.
* Make sure an online redo log group is archived (if archiving is enabled) before dropping it. To see whether this has happened, use the V$LOG view.
SELECT GROUP#, ARCHIVED, STATUS FROM V$LOG;
GROUP# ARC STATUS
1 YES ACTIVE
2 NO CURRENT
3 YES INACTIVE
4 YES INACTIVE
Drop an online redo log group with the SQL statement ALTER DATABASE with the DROP LOGFILE clause.
The following statement drops redo log group number 3:
ALTER DATABASE DROP LOGFILE GROUP 3;
When an online redo log group is dropped from the database, and you are not using the Oracle Managed Files feature, the operating system files are not deleted from disk. Rather, the control files of the associated database are updated to drop the members of the group from the database structure. After dropping an online redo log group, make sure that the drop completed successfully, and then use the appropriate operating system command to delete the dropped online redo log files.
When using Oracle-managed files, the cleanup of operating systems files is done automatically for you.
Your Database wont be affected as you can operate with 2 redo log files in each group as The minimum number of redo log files required in a database is two because the LGWR (log writer) process writes to the redo log files in a circular manner. so the process will hang becuase you are having 2 only groups if you want to remove 1 add a third one and make it the current group then remove the one you want to be offline.
Please refer to:
http://download.oracle.com/docs/cd/B10500_01/server.920/a96521/onlineredo.htm#7438
Kind regards
Mohamed
Oracle DBA

How to remove a redo log file

Hi Experts,
I want to remove a wrong redo log file from 10G R2 database in window.
how to do that without loss data?
my steps as
1. alter system switch logfile;
2. select * from v$log;
which ARC and sataus do I can drop redo log file based on above SQL
no archive and active status?
ALso Which account should I do above action?
fExamp, system account added redo log file, i only
can drop by system? how about sys?
Thanks help in detail steps
Jim
Edited by: user589812 on Dec 23, 2008 4:35 PM

Jim,
Check this link out for how to drop a redo log file
Make sure a redo log group is archived (if archiving is enabled) before dropping it. To see whether this has happened, use the V$LOG view.
http://download.oracle.com/docs/cd/B19306_01/server.102/b14231/onlineredo.htm#i1006489
SELECT GROUP#, ARCHIVED, STATUS FROM V$LOG;
   GROUP# ARC STATUS
        1 YES ACTIVE
        2 NO CURRENT
        3 YES INACTIVE
        4 YES INACTIVE
Drop a redo log group with the SQL statement ALTER DATABASE with the DROP LOGFILE clause.
The following statement drops redo log group number 3:
ALTER DATABASE DROP LOGFILE GROUP 3;

How to increase the size of Redo log files?

Hi All,
I have 10g R2 RAC on RHEL. As of now, i have 3 redo log files of 50MB size. i have used redo log size advisor by setting fast_start_mttr_target=1800 to check the optimal size of the redologs, it is showing 400MB. Now, i want to increase the size of redo log files. how to increase it?
If we are supposed to do it on production, how to do?
I found the following in one of the article....
"The size of the redo log files can influence performance, because the behavior of the database writer and archiver processes depend on the redo log sizes. Generally, larger redo log files provide better performance, however it must balanced out with the expected recovery time.Undersized log files increase checkpoint activity and increase CPU usage."
I did not understand the the point however it must balanced out with the expected recovery time in the above given paragraph.
Can anybody help me?
Thanks,
Praveen.

You dont have to shutdown the database before dropping redo log group but make sure you have atleast two other redo log groups. Also note that you cannot drop active redo log group.
Here is nice link,
http://www.idevelopment.info/data/Oracle/DBA_tips/Database_Administration/DBA_34.shtml
And make sure you test this in test database first. Production should be touched only after you are really comfortable with this procedure.

Dropping Redo Log Members

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